In order to switch electrical loads, an operating voltage with two potentials is applied to a series circuit consisting of a switching element and an electrical load. The electrical switching element, which has at least a first and a second switching state, is conventionally implemented as a mechanical element. Switching states are understood here to mean the “ON” switching state and the “OFF” switching state, the load being electroconductively connected to the operating power potential in the “ON” switching state, and cut off from this operating power potential in the “OFF” state. The “OFF” switching state will be referred to below as the first switching state, I, and the “ON” switching state will be referred to below as the second switching state, II. An operating voltage is understood here as either a DC voltage or an AC voltage. The term operating voltage is largely equivalent in the present invention to the term network voltage. In the European area, a network voltage of 230 V with a 50 Hz sinusoidal alternating voltage is currently provided by the respective network operators.
Switching elements are used for switching electrical loads in building technology, for example. The switching element generally switches only one conductor carrying a voltage or a current. This is predominantly the so-called L-conductor. L stands here for a line or live wire. As shown in FIG. 1, a normally mechanically formed switching element 8 is used here for switching electrical loads 3. The current-carrying conductor L is either connected to the load or cut off from the load.
These days electronic units are being provided more and more commonly. The electronic elements can be integrated into a switch arrangement. Thus, for example, an electronic unit for continuous or stepwise variable supplying of a potential to an electrical load can additionally be integrated into the switching element in order to dim light, for instance. An electronic unit can also be a radio receiver that receives a radio signal or electromagnetic radiation in general for switching the switching element. Corresponding to the radio signal, switching signals are generated by the radio receiver which place the switching element in one state or the other. Additional functions of electronic units in a switching element are likewise conceivable. Moreover, an electronic unit can also contain several units, such as a radio receiver, a dimming or regulating unit and/or a timer circuit. The electronic triggering unit of a relay that drives the mechanical part of the relay will also be considered an electronic unit below.
Electronic units hitherto required a so-called neutral conductor, also called an N-conductor, in order to perform their function. This N conductor serves as a return conductor and as reference potential of the electronic units in a switching element.
If electrical loads are wired with the structure described in FIG. 1, it has hitherto not been possible to supply the electronic units with power. It has also not been possible thus far to supply electronic units outside of the switching element with power independently of the switching state of switching element 8 if only one conductor carrying voltage or current in or out is available. Either switching element 8 is open in accordance with a switching state I, and then there is a potential difference across switching element 8 that could be used, for instance, to provide power to the electronic units. Or if switching element 8 is closed according to a second switching state II, an electrical connection is produced between switch terminals 801, 802 of mechanical switching element 8, and the voltage drop across switching element 8 is zero. A voltage supply element connected in parallel to switching element 8 would thus be bridged and would not supply any power for the electronic units in order, for instance, to put switching element 8 back into the first switching state I.